Such a case is known in particular by French Pat. No. 2,455,554. It comprises a body in which are integrally moulded a central post and a sleeve concentric thereto. The case also comprises a cover closing the body, imprisoning the tape reel of which the hub is centred on a single immobilizing ring surrounding the sleeve. The cover presents a central dish fitting in the sleeve of the body and on said post and defining a housing adapted to receive a locking device cooperating with this post.
In that Patent, the locking device is constituted by a single spring catch covering the post and guided in translation between the bottom of the central dish in the cover and a cap, which is fitted and fixed after assembly of the spring catch in said dish. This spring catch and the post of the body comprise mating engagement means capable of being meshed by a leaf spring integral with said spring catch and abutting on the lateral wall of the dish in order to provoke slide for engagement.
This known case presents the drawback of comprising four distinct pieces: the body, the cover, the spring catch and the cap, and consequently of requiring four operations of manufacture with four different moulds.
Furthermore, it is difficult to assemble on an automatic machine.
Locking thereof is not absolutely sure since it depends on the fixation of the cap.
Its cost is relatively high.
It is therefore an object of the present invention to simplify the design and construction of the locking device, as well as the assembly of the components, to reduce the number thereof from four to three, manufacturing them solely in plastics material, to eliminate the subsidiary assembly means by adopting an irreversible fit system and to render assembly easy, rapid and by means of an automatic machine. Consequently, the case may be mass-produced at a low cost price and with a reduced investment in tools.